Electrical switch.



0. S. WALKER.

ELECTRICAL SWITGE. APPLICATION 11,313 NOV. 30, 1909.

Patented July 2, 1912.

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0. S. WALKER.

ELECTRICAL SWITCH.

I APPLICATION FILED NOV. 30, 1909. 7 1,031,031 Patented July 2, 1912.

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OAKLEY S. WALKER, OF WORCESTER, MASSACHUSETTS.

ELEGTRICAL SWITCH.

Specification of Letters Patent.

Application filed. November 30, 1909.

Patented July 2, 1912. Serial No. 530,533.

To all whom it may concern:

Be it known that I, OAKLEY S. WALKER, a citizen of the United States, residing at Worcester, in the county of Worcester and Commonwealth of Massachusetts, have invented a new and useful Improvement in Electrical Switches, of which the following is a Specification, accompanied by drawings, forming a part of the same, in which Figure 1 is a plan view of an electrical switch embodying my present invention. Fig. 2 is a side elevation. Fig. 3 is'an end view. Fig. 4 is a front View of a modified form. Fig. 5 is a side view of the same. Fig. 6 is a detached view of the movable 3 switch bar.

Similar reference characters refer tosimilar parts in the difierent figures.

The object of my present invention is to provide an electrical switch adapted to be used in connection with the magnetized cores of a magnetic chuck, such as that described in Letters Patent ofthe United States No. 564,296, issued to me July 21, 1896. V

The purpose of my present invention to provide a switch which, by the ordinary movement of a switch bar, will enable the magnetic cores of a chuck to be energized during the operation of the chuck and demagnetized immediately upon the termination of the chuck holding period to allow the work to be removed.

Referring to the accompanying drawings,

1 denotes a base plate upon which the switch is mounted. Near the center of the base plate are posts 2 and?) in which a pair of switch bars 4 and 5 are pivoted, said bars being united at their free ends by a cross bar 6 provided with a handle 7. The post 2 is connected with the positive pole of an electric circuit by means of a wire 8, and the post 3 is connected with the negative pole of the same electric circuit by a wire 9.

The pivoted switch bars 4 and '5 when thrown over into the position shown in Fig. 2 are brought into electrical contact with the posts 10 and 11. The posts 10 and 11 with the wiring of the magnetic chuck bringing the latter into the electric circuit through the positive wire 12 and the negative wire 13, causing an energizing of the cores of thechuck. If the switch bars 4 and 5 be'raised out of contact with the posts magnetic cores of the chuck will be broken and the chuck will lose its magnetic power and allow the work to be removed therefrom. Suflicient residual magnetism, however, will remain to require force to remove the work which it is the'object of my present invention to obviate. Upon the opposite end of the base 1' I mount the contact posts 14 and 15. The post 14 is adapted to contact with the switch bar 4 and the post 15 with the switch bar 5. The posts 14 and 15 are connected by the crossed wires 16 and 17, indicated by broken lines in Fig.

1, with the posts 10 and 11 respectively, If the switch bars 4 and 5 be brought into contact with the posts 14 and'1-5 and allowed to remain, the electric current will be reversed, the wire 12 then becoming negative and the wire 13 positive through the connection of the posts 10 and 11 with the posts 14 and 15 by means of the crossed wires 16 and 17. This operation of the electric switch bars 4 and 5, while itwould accomplish the momentary demagnetization 'of the chuck would result in the permanent .magnetization of the chuck by an electric current moving in thereverse direction, causing the work to be as firmly held upon the chuck as before, and only permitting the work to be removed during the momentary period of demagnetization. In the use of magnetic chucks it frequently happens that a large number of pieces are held upon the chuck at the same time, and while the momentary demagnetization of the chuck might allow a single piece of work to 'be removed, if done quickly, and at the precise moment of demagnetization, the reenergizing of the chuck would occur before all the pieces could be removed.

In order to the magnetic coresof the chuck by the reverse electric current 1 construct the posts 14 and 15 so that when the switch bars 4 and 5 are swung over from the position shown by solid. lines to that shown by broken lines in Fig. 2, they will pass the cont-acting surfaces 18 of the posts 14 and 1.5 between the points 19 and 20, and enter the prevent the reenergizing of wide spaces between the base sections 21,.-

21 and out of contact with the posts 14 and 15. The speed of the movement of the switch bars 4 and 5, as most conveniently manipulated, being ascertained, the period of contact of theswitch bars with the posts' 10 and 11, the electric circuit including the l 14 and 15- will be determined by the length tact with the posts 10 and 11, causing the energizing of the magnetic cores of the chuck by an electric current in which'the wirel2 is positive and the wire 13 negative. When the work is to be removed from the chuck the switch bars 4 and 5 are carried from the position shown in Figs. 1 and 2 to that indi'cated by the broken lines 5, Fig. 2, cansing the switch bars to pass rapidly by the contact surfaces 18 of the posts 14 and 15 and into the wide space between the bases 21 of the posts. During the contact of the switch bars at and 5 with the contact surfaces 18 the reversal of the electric current is accomplished, the wire 12 becoming negative and the wire 13 positive. By adjusting the extension pieces 22 relatively to. the speed at which the switch bars are moved the period of contact with the surfaces 18 may be determined, and the reversal of the current continued only so long asrnay be required to accomplish the complete demagnetization of the chuck.

In Figs. 4- to 6 inclusive, I have shown a modification of my improved switch illustrating the application of my invention to a grinding machine comprising astationary framework 24. and a movable member A base plate 26 is attached to the stationary framework 24 of the machine provided with contact surfaces 27 and $28, electrically connected by wires 29 and 30 with binding posts 31 and 32, the contact surface 27 being con nected with the post 31 and the contact surface 28 being connected with the post 32. In alinement with the contact surfaces 27 and 28 are contact surfaces 33 and 34, the contact surface 33 being connected with the binding post 31 and the contact surface B l being connected with the binding post 32. From the binding posts 31 and 32 wires 35 and 36 lead to a magnetic chuck. Attached to the movable member 25 is a switch bar 37 supporting the cylindrical chambers 38 and 39 containing the metal balls 40 and 41, which are held against the contracted outer ends of the chambers by means. of spiral springs 42 and 43. The balls 40 and ll are electrically connected by wires 44 and 45 with a source of electricity,

the ball 40 forming the positive pole and the ball 41 the negative. The movement of the movable member is preferably limited in one direction by a stop and in the opposite direction by stop 4?. said, stops being omitted.

so adjusted that when the member 25 is moved by handagainst the stop 46 the balls 40 and ll will be held in contact with the contact surfaces 27 and 28 forming an electrical communication with the chuck in which the wire 35 is positive and the wire 36 negative. "When the movable member 25 is moved in the opposite'direction against the stop at? the balls 40 and 41 will be moved entirely across and in contact with the contact surfaces 83 and 34 into'the position shown in Fig. 4, in which each of the balls 40 and 41 are spaced from the contact surfaces 33 and 34.

During the period of contact of the balls 40 and e'l with the contact surfaces 33 and 34 the wire 35 is rendered negative, and'the wire 36 positive through the connection between the contact surfaces 33 and 34 and the binding posts 31 and 32'by means of the wires 48 and 49, thereby reversing the direction of the electric current. The contact surfaces 33 and a are each of the proper width relatively to the speed of the moving switch bar 37 to affect the demagnetization of the magnetic cores of the chuck. Of course when the movable member 25 mechanically moved by the operation of amachine so that its amplitude ofmovement is predetermined the stops 46 and 47- can be I am aware that it is not new to successively energize a magnetic core by a series of reversals of an electric current for the purpose of demagnetizing other articles which are brought into and gradually removed from the field of the magnetic core.

Devicesof this class have been employed for the purpose of demagnetizing articles which had become magnetic, such as watches, tools, etc. In all devices of. this class, however, the objecthas not been to de magnetize the magnetic core but to successively energize it by means of series of electric currents in opposite directions, thereby reversing the polarity of the magnetic core, and utilizing its effect upon other articles for the purpose of demagnetizing them. The object of my present invention is not to demagnetize articles by gradually bringing them into and gradually removing them from the field of a magnetic core whose polarity is successively reversed. The object of my present invention is to energize the magnetic cores of the chuck by a direct current during a desired work holding period and then completelydeniagnetizing the chuck to allow the work to be removed.

I claim,

1. An electrical switch com risin movable switch bars having a predetermined amplitude of movement, contact surfaces at eneend of their movement, contact surfaces spaced from the other end or their movement, said second contact surfaces being connected with said first contact surfaces by crossed wires.

2.' An electrical switch, comprising movable switch bars, contact-surfaces at one end 5 of their movement, contact surfaces of limited area spaced from the opposite end of the movement of the switch bars and from the first contact surfaces, and crossed wires electrically connecting said first and second contact surfaces.

3. An electric switch, comprising mov able switch bars having a predetermined OAKLEY S. WALKER.

Witnesses PENELOPE COMBERBACH, NELLIE WHALEN.

' Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

, Washington, D. C. 

